Triphenylphosphine → 1-(4,5-Dihydro-1,3-thiazol-2-yl)azetidine-3-thiol--hydrogen chloride (1/1)

To a solution of 22.7 mg of 3-mercaptoazetidine hydrochloride (12) obtained in the above Example 11 dissolved in 95% methanol (including 1 ml of water), there were added 26.6 mg of 2-(methylthio)-1,3-thiazoline and 5.2 mg of triphenylphosphine, and the resulting solution was subjected to heating and reflux for six hours. After the reaction was over, the solvent was evaporated in a vacuum, and the obtained residue was dissolved in a 0.1N hydrochloric acid, and the resulting mixture was washed with ethylacetate. The solvent in the obtained aqueous layer was evaporated in a vacuum, and the obtained residue was separated and purified by high performance liquid chromatography, and, thus, there was produced 29.1 mg (yield: 73.4%) of 3-mercapto-1-(1,3-thiazolin-2-yl)azetidine hydrochloride (8) in the form of colorless needle crystal.